Comminuting constitutes reducing materials to smaller sizes. This can be accomplished with pulverizing, cutting, or other means.
Garbage, trash, and refuse pose special problems for conventional comminution methods. The material to be comminuted has a wide range of size, length and composition such as hardness. The same load of garbage or refuse may contain lumber, rocks, earth, glass, metal and plastic along with softer materials such as paper, cloth and cardboard.
This traditionally has not been a problem since large pieces of refuse or garbage could be disposed of in sanitary landfills. However, in some areas and in the near future, this option is or may rapidly disappear. Landfill space in some areas, if available at all, is at a premium. Additionally, the Environmental Protection Agency has mandated additional requirements, limiting this method of disposing of garbage or refuse.
In many areas, refuse and garbage are being burned or converted to less hazardous states. This burning or other conversion invariably requires a more uniform size of particle than is required of garbage or refuse to be stored at a landfill. Such conversion requires small, even sized particles because they are easier to handle and they burn much more rapidly than do larger pieces of material.
The existing technology has proven inadequate for efficiently reducing such a wide range of materials to small particles, regardless of the consistency of the materials being comminuted.
A large number of patents discuss comminution of one material or another. For practical reasons, the discussion of patents and other art immediately following is limited to those methods and apparatuses believed to be the most relevant.
U.S. Pat. No. 5,082,188 to Urich discloses a vertically mounted two chamber comminuting machine, with fliting attached to a cone in the first chamber to form a screw. The first (feed) chamber is conically shaped, as contrasted with a generally cylindrically shaped chamber (or multi-sided polygon shaped chamber) found in the instant invention. This conical shape works well when comminuting hay bales (the subject of the Urich patent), but was never designed to comminute refuse or garbage. For example, pieces of lumber fed into the machine would often be flung out of the machine, endangering both operators and nearby equipment. A vertical orientation is not as effective as the horizontal orientation used in comminuting the range of materials found in refuse and garbage. Finally, the Urich patent invention does not disclose the use of holding bars for holding long pieces of material.
U.S. Pat. No. 2,701,595 to Berger discloses a two stage comminution machine, with horizontally mounted rotating cylinders located in each comminuting chamber. The invention is attached to the front of a harvesting machine such as a combine. At a minimum, the Berger patent does not disclose the use of longitudinally extending, generally planar sides in the lower portion of the first comminuting chamber or a seven-sided polygon shape for the first comminution chamber, the use of holding bars, or the use of removable blades.
Additionally, the inventor of this invention is aware of at least one instance of a vertically oriented screw mounted in a multi-sided polygon. However, in that apparatus, the screw was limited in its use to simply move material. In any event, that apparatus was not used nor 10 did it perform comminution.
Prior art apparatuses were disadvantageous because the comminuted material would frequently wedge or pack between a rotating drum (which carried the reducing means) and the housing for the drum. Other apparatuses were ineffective in comminuting longer pieces of material contained in the material being reduced.